AM3+ is an older series, of course there will be no DDR4
as far as pins on the CPU i see no downside besides personal choice
As far as I know AMD will no longer be making AM3+ Processors, as they have begun to move their FX line to the FM2+ Architecture, you can find some of their new FX APU's in some higher end AMD based laptops.
Its unknown when they will bring the fx series to desktops though but I expect it to be soon once this laptop exclusivity BS is over.
Also OP funny you blame Windows 10 considering I'm running a old Single core Celeron Laptop in Windows 10 and it performs perfectly, if anything its probably your motherboard's BIOS that may need updating.